Severe combined immunodeficiency (hereinafter referred to as ‘SCID’) occurs in humans (Buckley, R. H. Annual review of immunology 22, 625-655 (2004)). However, an agent for treating SCID was not easily developed due to limited animal models reflecting the type of human SCID. Pigs have physiological characteristics similar to those of humans, and mimic many human diseases with a similarity higher than rodent models (Whyte, J. J. & Prather, R. S. Molecular reproduction and development 78, 879-891(2011)). Thus, SCID pigs can represent models that mimic human diseases. In addition, SCID pig models can be used in cancer research, cell transplantation, and drug development research.
Interleukin 2 receptor gamma (hereinafter referred to as ‘IL2RG’) is associated with X-linked SCID types, and IL2RG mutations cause deficiency of T and NK cells and functionally impaired B cells in mice (Cao, X. et al. Immunity 2, 223-238 (1995)). X-linked SCID pigs generated by disruption of IL2RG were recently reported, which exhibit human X-linked SCID phenotypes (Suzuki, S. et al. Cell stem cell 10, 753-758 (2012)).